Rail expansion joint applied to the IIA's demonstration line has similar feature to the shape that is rail expansion joint of the Japan's LINIMO, It can secure running-stability of train as the formation of opposite surface of continuous gap sensor, and ensure track structure stability about displacement by expansion contraction of bridge. However, the rail expansion joint has limitations to slim structure through the continuous of superstructure because the maximum displacement is limited to 80mm. Therefore, this study propose a shape of rail expansion joint which can secure the stability when expansion or contraction at bridge deck ends and rail ends occurred more than 80mm, and the structural stability was verified through the finite-element method analysis.